This invention relates to the field of metal ion separation chemistry and, more particularly, to solvent extraction. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).
Acidic effluent streams containing elements of the actinide series and lanthanide series of the periodic table are generated in certain nuclear energy applications, such as the processing of waste from light water nuclear reactors. Processing of certain ores produces acidic process streams containing metals from the actinide and lanthanide series. The actinides can exist in a hexavalent state, a tetravalent state, or a trivalent state. The lanthanides usually exist in the trivalent state. Most other metals which may be present in actinide-lanthanide systems are in the monovalent, divalent, or trivalent states. It is desirable to be able to separate any and all of these metal ions from one other for a variety of reasons. For example, in the processing of monazite ores that contain high levels of the tetravalent actinide metal, thorium, and many of the lanthanide metals, it is desirable to produce pure lanthanides by quantitatively separating the thorium from the lanthanides. Also, it is desirable to obtain the thorium in pure form. Further, it is often desired to perform separations for purposes of recycle, waste processing, and analytical characterization.
The 1,3-diketones have been extensively studied as extractants for actinide and lanthanide ions (see item 1 on the list below for the citation to the paper for this statement). The linking of multiple 1,3-diketone units to give compounds with increased binding constants for U(VI) and some lanthanide ions has been reported. Alberts and Cram (2, 3) prepared a series of linear and macrocyclic ligands containing two or three 1,5-substituted acetylacetone units. These tetradenate compounds showed increased formation constants for divalent ions, including U(VI), of two to four orders of magnitude when compared with the unlinked bidentate analog. The compound containing three acetylacetone units showed a corresponding increase of five to six orders of magnitude in the formation constants with La(III), Ce(III), and Cr(III) over the bidentate analog. Tabushi et al. (4) reported on the preparation and extraction properties of a macrocycle containing three 1,3-diketone units, but the bidentate analog was not directly compared in this study. Extraction data for U(VI) has been reported for the linked pyrazolone 4,4'-decanedioyl-bis(2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one) by Jiasheng (5 ), but no comparison with the bidentate pyrazolone was made.
The full citations for the papers mentioned above are as follows.
1. Sekine, T. and Y. Hasegawa, Solvent Extraction Chemistry, Marcel Dekker Inc. New York, 1977, pp. 179-186, (this is a book). PA1 2. Alberts, A. H. and D. J. Cram, J. Amer. Chem. Soc., 99, 8366 (1977). PA1 3. Alberts, A. H. and D. J. Cram, J. Amer. Chem. Soc., 101, 3545 (1979). PA1 4. Tabushi, I., Y. Kobuke, and T. Nishiya, Tetrahedron Lett., 37, 3515 (1979). PA1 5. Jiasheng, D., The Extraction of Uranium (VI) With 4,4'-decanedioyl-bis(2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one), J. of Nuclear and Radiochemistry (1985).